Plastic bottles and other similar containers are widely used as containers for retailing soft drinks and other beverages. One type of plastic, polyethylene terephthalate (PET), has become particularly popular because of its transparency, light weight, and low cost. In addition to being flexible, the walls of PET bottles are strong in tension and thus can safely contain the pressure of a carbonated beverage. Moreover, conventional PET bottles can bear surprisingly high compressive loads, provided that the load is directed substantially along an axially symmetric axis of the bottle. A single PET bottle can support the weight of many bottles of the same size filled with beverage if the bottle is standing upright on a flat, horizontal surface and the weight of the other bottles is applied to the closure of the single bottle and is directed substantially vertically along the symmetric axis. However, if a compressive load is applied to a conventional PET beverage bottle along a direction other than the symmetry axis of the bottle, the bottle tends to buckle. This tendency of conventional PET bottles to give way under off-axis compressive loads is particularly pronounced for large capacity bottles, such as the two-liter bottle widely used for marketing soft drinks.
Soft drink bottles are ordinarily packaged by bottlers in cases or other containers, several bottles to the case, for shipment to retailers or for storage. Cases of bottles are customarily stacked on top of each other. In warehouses, cases of bottles are frequently stacked on pallets which can be lifted and moved about by fork-lift trucks. The stacks of cases on the pallets must therefore be particularly stable in order to remain standing in the face of the jostling inherent in being moved about. A technique for interconnecting columns of cases, called “cross stacking,” is often used to improve the stability of cases of bottles loaded on a warehouse pallet. Cross stacking generally involves stacking rectangular bottle cases to build up a layered structure, with each layer having cases oriented parallel to each other and with the cases in adjacent layers being oriented at right angles to each other. Since each case in the cross-stacked layer rests on at least two cases in the layer below, the cases of the cross-stacked layer tend to keep the cases on which they rest from moving apart from each other. The cross-stacked layer therefore stabilizes the structure.
Because of the tendency of conventional PET beverage bottles to buckle under off-axis loads, attempts to stack cases of these bottles give rise to serious problems. Bottles can tilt away from vertical alignment upon stacking if conventional partitioned cases having low side walls are used to contain the bottles. Tilted bottles in the lower cases of a stack can buckle and give way, causing the stack to fall. Even absent buckling, the tendency of bottles to tilt in conventional low-sided cases causes problems. Tilting generally places an undesirably low limit on the number of tiers in a stack since the tilting of bottles in one case can cause the next higher case in the stack to tilt. This leads to instability if too many tiers are included in the stack.
Previously, these problems were dealt with by packaging beverage bottles in corrugated-paper cartons having high sides, often equal in height to the height of the bottles. Two-liter PET bottles filled with soft drinks were often packaged in enclosed corrugated paper cartons for storage and shipment. Although the high sides of these paper cartons reduce the incidence of tilting and provide additional support when the cartons are stacked, the cartons are expensive. The cost of the cartons cannot ordinarily be distributed over a number of repeated uses since corrugated-paper cartons generally are not rugged enough for reuse and therefore they are usually discarded by the retailer.
One solution to the problems of full depth corrugated-paper cartons is plastic full depth cases. In plastic full depth cases, the sides are load bearing. Full depth plastic cases also have numerous disadvantages. They are expensive to manufacture. They are also expensive to ship and to store empty in a user's warehouse as they require a great deal of space. Also, they may totally or partially surround the bottles, thereby preventing or minimizing the display of the bottles.
To overcome these problems plastic low depth cases have been used. A low depth case is one in which the side walls are lower than the height of the stored bottles or containers, and in which the containers support the weight of additional cases stacked on top.
Such cases may be stacked high above a person's head, may be placed low on the ground, or anywhere in between. However, providing a means to lift, carry and handle such cases is often difficult due to space and size considerations for the case and its environment. In other words, additional case details and features typically lead to larger overall dimensions for the case, and therefore reduces the amount of product that can be placed on a pallet or in a truck. Additional case details typically also means that the cases do not sit comfortably upon a pallet, but instead may overhang the sides, which is not a desired result.
Consequently, there is a need for a container case of the low depth variety which is efficient in terms of design size and shape. Such case design should be capable of placement on a standard pallet with other similar cases so that it fits with little or no overhang. This case should also include a manner by which to carry and handle the case which does not interfere with the efficiency of the design, and allows the case to be handled or lifted at any number of contemplated heights at which it may be stacked or rested.